1. Technical Field
This disclosure relates to controlling access to a wireless communication system by mobile communication devices while near or within a security zone.
2. Description of Related Art
Mobile communication devices are widely available and in common use. However, their use in some areas may not be desired.
In prisons, for example, mobile communication devices are sometimes used by inmates for illegal purposes, such as to manage criminal enterprises and/or to harm or intimidate witnesses.
Efforts to prevent such problematic uses may not always be successful.
In prisons, for example, visitors may be searched and cell phones which they carry may be removed before they enter a security zone. However, these searches may not always be effective. For example, a small cell phone might be missed during a search, or a guard might be persuaded to allow a mobile communication device to enter the security zone. Searches may also not prevent mobile communication devices from being delivered into a security zone using airborne projectiles.
Dogs have also been trained to locate cell phones by their smell. The effectiveness of such an approach, however, may not yet have been proven. Even when a cell phone is uncovered and removed, moreover, the supply of such devices may be so plentiful as to enable it to be easily replaced.
Detectors have been set up to detect the transmission of communications from wireless communication devices. Cameras have then been activated in an effort to search for the users of these devices. Again, however, the procedure may not be entirely effective. And, again, a confiscated phone may be easy to replace.
Local jamming is another approach which has been employed. However, it may be difficult and/or expensive to restrict the jamming to only the secured area. As a consequence, mobile communication devices outside of the secured area may also be jammed. In an effort to minimize excessive jamming, the jamming level may be set low, but this may reduce the effectiveness of the jamming within the security zone. Users within the security zone who should be permitted to use mobile communication devices (e.g., prison guards), moreover, may also be blocked from doing so.
Microcellular communication cellular systems have also been used to manage communications within a security zone. However, these systems may be costly and may interfere with a global wireless communication system that otherwise would manage these communications.